feed: fix link rendering

some words were incorrectly detected as links.

changed:
- split words by any whitespace character, not just char 32
- match words _beginning_ with http, https or www.

example of broken link user white space character code 160, see:
feb290999a2746bf0914ede8a811b52eccd423f9f5373232e4f5947131fb47aa

src/domutil.js

@@ -57,14 +57,14 @@ export function parseTextContent(string) {
         .replaceAll(/\n{3,}/g, '\n\n')
         .split('\n')
         .map(line => {
-            const words = line.split(' ');
+            const words = line.split(/\s/);
             return words.map(word => {
                 if (word.match(/^ln(tbs?|bcr?t?)[a-z0-9]+$/g)) {
                     return elem('a', {
                         href: `lightning:${word}`
                     }, `lightning:${word.slice(0, 24)}…`);
                 }
-                if (!word.match(/(https?:\/\/|www\.)\S*/)) {
+                if (!word.match(/^(https?:\/\/|www\.)\S*/)) {
                     return word;
                 }
                 try {